Gene Simmons & Shannon TweedTie the Knot

10/2/2011 5:30 AM PDT BY TMZ STAFF

After 28 years together, Gene Simmons and Shannon Tweed finally tied the knot yesterday at the Beverly Hills Hotel.

Among the nearly 400 guests were Hugh Hefner, Bill Maher and the members of KISS ... including Paul Stanley, who was in the wedding party.

We're told Tweed was wearing $2.5 million of diamonds for the first dance ... and that does NOT include engagement ring. Michael Raven handmade the jewelry -- which included 13 pieces for the bride and bridal party, consisting of earrings necklaces and a $420,000 bracelet.

The couple's two kids -- Nick, 22, and Sophie, 19 -- were also there, with Sophie serving as maid of honor.